Length-weight relationship, condition factor and relative condition factor of Alosa braschnikowi and A. caspia in the southeast of the Caspian Sea (Goharbaran)

The main objectives of the present study were to determine the species composition of Caspian shad, genus Alosa and to estimate the LWR, CF, and Kn of A. braschnikowi and A. caspia during different months in the southeastern coast of the Caspian Sea. Two fishing methods, small mesh size beach seine and gillnet were used from December ۲۰۱۳ through July ۲۰۱۴. A. braschnikowi and A. caspia, were distinguished in the southeastern part of the Caspian Sea (Goharbaran), consisting of ۵۷.۱% and ۴۲.۹% of the Alosa catch, respectively. The slopes (b values) of the length-weight regression were ۳.۲۴۱ and ۲.۸۴۴ which were significantly different from ۳ (P<۰.۰۵), indicating positive and negative allometric growth, respectively. The average CF of A. braschnikowi and A. caspia were calculated as ۰.۷۲ ± ۰.۱۲ and ۰.۸۳ ± ۰.۱۳, respectively. The average CF for both species were significantly different among months (P<۰.۰۰۱). There was a significantly negative correlation between size classes and CF of A. caspia. The Kn was greater than ۱ for A. braschnikowi and lower than ۱ for A. caspia indicating good well-being of A. braschnikowi as opposed to A. caspia in the southeastern Caspian Sea.

کلیدواژه ها:

Shad ، length ، Condition factor ، Relative condition factor ، Caspian Sea